Function: cubicspline
Purpose: Cubic spline through X and Y positions.
Category: MATH
File: cubicspline.c
Author: M.G.R. Vogelaar
Description: Piecewise cubic spline trough 'np' two dimensional positions
stored in arrays 'X' and 'Y', using 'cord' approximation.
See 'Mathematical Elements for Computer Graphics', 2nd ed.
David F. Rogers, J. Alan Adams. p. 262.
Use: void cubicspline( float *Xus,
float *Yus,
int np,
float sampdist,
float **XusO,
float **YusO,
int *nout,
fint *blo,
fint *bhi,
float *splineleningrids )
On input the variables Xus and Yus contain the contol points of
the spline. The number of points is 'np'.
'XusO' and 'YusO' are pointers to arrays and are set to NULL.
In the function 'cubicspline' memory is allocated for these arrays.
You need to free memory in the calling environment.
On output, these arrays 'XusO' and 'YusO' contain 'nout' positions that are
interpolated along a cubic spline on a sample distance given
by 'sampdist' (usually 1).
Also the length of the spline in grids is returned ('splineleningrids').
Remarks:
Updates: Jul 26, 2004: VOG, Document created.